They pick anything they can find which is suitable.
When bird find mate they will build a nest
The doctor bird uses silk from the spider web to build their nest.
Birds build their homes out of materials that they find outdoors. Bird's nest are often times built out of dry leaves, sticks, and grass.
There is no such bee species.
in a tree
That's a bird-so a bird best, if you mean how do they build-specify
female
penguins don't build nests
It is a heterogeneous collection of twigs, leaves, bird down, and other materials.
three
in a palm tree
maybey